Playwright Testing for Feature Flags and A/B Testing Platforms

This guide provides complete, production-ready Playwright patterns for playwright testing for feature flags and a/b testing platforms.

Introduction

Robust test automation requires domain-specific patterns. This article covers playwright testing for feature flags and a/b testing platforms with practical code examples you can use immediately in your test suite.

Architecture Overview

graph TD
    Test["Playwright Test"] --> App["Application Under Test"]
    App --> API["Backend API / Mock"]
    API --> Assert["Test Assertions Pass"]

Implementation

test('feature flag controls new checkout UI visibility', async ({ page }) => {
  // Force feature flag to enabled
  await page.addInitScript(() => {
    window.__FEATURE_FLAGS__ = { newCheckoutUI: true };
  });
  await page.goto('/checkout');
  await expect(page.getByTestId('new-checkout-v2')).toBeVisible();
  await expect(page.getByTestId('old-checkout-v1')).not.toBeVisible();
});

Run Tests

npx playwright test --grep "Playwright Testing for"
npx playwright test --ui

Reference Table

Best Practices

Common Mistakes

Frequently Asked Questions

How to force feature flags in Playwright tests?

Use page.addInitScript() to set window.__FEATURE_FLAGS__ before the app initializes.

How to test LaunchDarkly flag changes?

Mock the LaunchDarkly SDK evaluation method and return controlled flag values for each test.

Can Playwright test A/B test variants?

Yes, force a specific variant assignment and verify the correct variant renders consistently.

How to test feature flag gradual rollouts?

Set the flag to return true for 100% of users in tests to consistently test the enabled state.

How to test kill switches that disable features?

Set the flag to false and verify the feature is completely hidden and no console errors occur.

Summary

This guide covered playwright testing for feature flags and a/b testing platforms. Apply these patterns to build reliable, fast, and maintainable automation for this specific scenario.

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